Train control



MayI 24,1927., f

Cl A. CAMPBELL ET AL TRAIN CONTROL Filed Jul, 1926 2 Sheets-Sheet l By r11/n. Cf Wolzzalz,

Y, @am TORNEYS,

- connection 12 leads by way lof themain reservoir port loto the space within thecap 16 above the usual rotary vvalve 17. Similarly, thefeed connection communicates with the feed lport 18 and the brake pipe connection with the brakepipe port 19, eachk of which portsterminates in the seat ot the rotary valve 17. Y

There is an exhaust port 2O whichhas two branches, terminatingon the seat of the Yro-r tary valve, a preliminary exhaust port 21 .o

which'le'ads from the space above the equalizing piston to the .seat ofthe. rotary valve,

and an equalizing res-ervoirport 22. There are other ports visible in the drawing, but since theyv are forlrnown purposes and not-- they Yconcerned with the present invention need. not be further:discussed .20. ated bythe equalizing discharge piston, 26.

The usual equalizing discharge valve 24 controls a dischargefport 25 and 'it` is actu- The space below this piston is connected by a a'passage 27 with the brake pipeV port 19, j while the space above the piston is connected with the equalizing reservoir hereinafter described, by way otpassage 2S and connection'29. f V i "i As stated,` the preliminary exhaust port is controlledby a stop valve, and this valve includes a seat 30,1 a needlevalve 31 enacting therewith, an armature'32connectedto the needle 'valve for actuating` theA same, and an electromagnetic Winding 33 for actuating the brake valve` `but after the brake valve rhas been movedto service position ,automat-i-v vcally, and after adeinite pressure reduction 1n the equahzing reservoir has occurred," the eoil'33 is energized Vby automatic means, terminatngthe discharge ot' pressure from- 'the -equalizing reservoir. It is this windingV whichV is vexcitedto terminate each ofy the successive reductions and 'deenergized to initiate .eachsucces'sive reduction after the iirsti.

Attimes, as a result of'derangement of the Vwiring., it might be necessary to cut out ythe 3d is provided whichy has a port 35, throu needle valve 31. Consequently, a. rotary cap which 'the preliminary exhaust' port 21 bis lnormally connected (seeFigure 1). {This cap has another portV 36 which is rendered etfective by the rotation of the cap 34 to an abnormal position (see Figure 5), and when effective. establishes a by-pass around the valve31 and its seat 30. As the rotary cap '34 is merely an emergency appliance itis normally sealedin the position shown in `Figure 1 to prevent unauthorized turning of the. cap.V

The rotary yvalve 17 has a feed groove,V 37

through which the brake pipeport 19 is fe'd fromthe feed port 18 in running position.

vrlhis is thenormal condition 'ot' the parte @h Vlrport 56.

lthe cylinder 47.

Another passage effective in running oposition-is the passagedwhich a, establishes an equalizing connection between'the brake pipe port andthe equaliZin-'g reservoir. -fgln'serv- 'ice positioni'(se e Figure t) theipassage 39 f connects the preliminary exhaust 'p'ortv21 with the exhaust port 20, Land isthefport reservoir is reduced ito bringfabouta service reduction of brake pipe'pressure.,.V It seems` unnecessaryto.describe the other throughvvhich the pressure vin the equalizing .l

Jassae'es in the rotar 'f'.valve as these are of usual t'ormv andA have no1 novel function in :connection with"y ,theV present'kinvention. `lt

may be noted, however, that the` valve is loi the ordinary equalizing discharge type having the usual positions known asvrelease,r running, holding, lap, "service, and` emergency, together vwith'theusual functions core responding to such positions.

The rotary valve 17 turned onits seat by means Vlof a stem 1() which is provided with the usual handle 41./ The handle-lis provided with a sector gear 42 which meshes" with a rack 13 and theracl: t3'is longitudinally slidable in a guideway 44. The raclr 43 is rigidly connectedto a piston rod 45 'which is iny thrust relation with apiston l-t'slidable inY a cylinder 47. jThe parts `areso dimen-v vsioned that when the pistonl6 moves to limit of motion in a lett., hand direction it will move the valve handle l1 .to lservice position. A port 48 leads from the space within the cap 16 above therotary valve 17 past the lOl) valve seat 119, which is'controlled by aneedle valve 50. This valve is actuated throughan armature 51 bya winding 52, the parts being` f so arranged that when the winding 52 is eX- cited the valve 501s closed `against 'its seat.`

Deenergization ol ,the winding permn Ythe valve 50 to open, whereupon main reserfvoir air entering 5the cylinder t7 through the port 18 moves the engineefs brake valve to iis Some means must be provided to'preventthe action of the piston 4-6 should the elec trical mechanism for exciting the coil i 12e become deranged. Consequently a ralveis used consisting ot a rotary cap 5-1 having a port 55. Then sealed in itsnormal position f vshown inl Figurefl', this port serves merely Mounted below the dischargeport fot Y the equahzm'g"discharge valve 24 and in llo service application position. luring such j communication with seid' port,A is at cylinder 57"n Whichis. et pistonl 58 urged Upward by Spring' 59 is so chosen their .it vWill beV overpowered by the discharge preszi spring 59.

establishedmanually, a' posh 'button sivizteh' V 62 is' connected across thetermins-ls 6'0 and 61', but. it will be understood that 'the evite-hij" 62 s'norinally' open and must be held Closed" manually.. l

The nections hereinafter described bymeans of fr time yswitch consisting of e iixed Contact t aresilient piyoteo contacter Get, er solenoid Winding 65 ivithmoviible Core 66V connected to act-nate the Contacter, and having fi re'- tarding device consisting'ot :i plunger 68- in :i dash pot 6.?. with e through port 69, so dimensionede's to Hive the desired timing Chzireeteristie A iqpid is used yin the dash pot as the retard ing fluid.. This valve is so arranged that it closes in ashort'period,v sity one or two see# onds, flexing the resilient contacto-r 64.'

i Vhen the lcoi1`65 is deeiiergizedthe opening v movernenty is relatively sto-Wer, the prirpose Yvolume of the shell serves'iito vthe left 'larger chamber cominen'eeslto'ull as @result ofthe'delayed opening bet-Ween' the oontaoe tor .64 zindthe-eontact being` to permit eer-V V tain-pressure equeh'zat'ions -tooccur in. the

for limiting' brake pipe re valve mechanism duct-ion'. Y

This mechanism is associated with a' Vspe-y cial'type of equ-zrlizing reservoir which `Will n'oW be described.v Instead of the usuel reservoir a shell .70- d'ivided by a partit-ion 7l into two iin-equalchembers is eonneotedtto connection 29.' These vtivo, eli-(1mbers\` :ire normally in Communication through ports "Z2 and 73.' This co-miniiniezrtioiif is oontifolled lby zineedlle velve which seats oii a "seat Tllythe valve: being electrically eolitroll-ed by meot-ns ot':i1i' 2rrmatiiier6. which actuated by `a Winding 77. Norn'izilly' the Winding Wis deeii'ergized so that the valve 75 is open andthe two chambers irrexin Commiiniezition with eachother. hi tl e entire no-rn'ia-l conditions Ai.. e, (during miinrizil operation of the eng'ineers brake .elve)`'zi s he equa-lizin;i reservoir. The Winding-7T is controlledV by the switching" act-ion the piston 58- so that While the eqiifoliino dis'elm-rge valve 24 is opembiit only during.` :iii applicationziiito= maticiilly produced, the Winding; 7 is enei'g'ized. Thus. as sonnes an'iriitoimrti cally produced application commences, the. smallfehnmber to the right 'ot the portition 71 is' isolatedifrom iheinirger eli'amber thereof, and the pi'essiiie'in 'the obteinedyeiidt n rise or" e lozided diephregm i f' The' dii.

Winding 33 is controlled. through colifeltrmped between geeft-'Qns .of shellv ,whiieh' i The' plunger @Sie provided ot theshell 70. pr

'retiirn- 'for the apporti-tirs speoe tothe lett of the partition lserve'sthe eqiializing reservoir. A i

. llt is one or tion as soon/ as ade tii reduction! has been is seeuiied by the j'eet tofthef o'liposing.pressures ot: the` tryo Chambers to YThe@amount that the die-phrf determines the pressure oft A tion limi ti"f devieeaots. i ephragm is shown at Z8-1.v` and is the purposes of this inventioiif `to terminate the brake pipe Vpressure ifediie-y ris i Y 75 ytherightsind to the left ot the partition 71."

is loaded xvl'i'ielfii the'rediio-I f f forms s; sort Yof" extensionfoi'v the shell 'Z`. l'

The diaphragm 'issubjecton' its loiver1 side to pressure in the smsll'eif'* or right hand ripper` side the diepliriigni is subject to' the' pressure in theflsrf 'nor lett hond ohr-tmber' ie arriving by Waiyof ports T2 and T9. The dia-phragn'i is clamped]Y plates 8 0 Whiehcfirry- .81"v and exe s'- a downwardithrust on the displiigin. The

Slid'ebly ni imtod on .the donn-Ward eX- tendilng stemiS is 9. sleeve S6? ivlii-ohis urffedf riprvzird relatively tothe sten-i by a? ht spring; n Thesleeve 8:6 Cei-ries annular flange Contact 88 which is insulated aft- 89' vfrom the sleeve. :ind which on: iipWa-rd move-l n'ient oft` `the diaphragni engages tivo `coni' in .platee and `sealed The pnipose ot the/"s yielding; coiitfiiet endl. n on the-.Conte 90 and The eleetrieell Connection iioiis pn ts so fer ;(leseiii lf sire as followedV The ivi-re leads to coiitziiet'f' und thence the stress exerted to one terini'naloit win :om the otllier'-` vivire Q'yleedsto tl'iefroi'iteet 90 of the red: etion limiting' device. eind-"another Wii 98 Lf*fi-oinf-the ,otlir 'oon reduction limitingrdevi y e 9o leads eoiiltziet 63 s between rae" e 4 i ie? to ne end of the Winding 65 of `the tin'ie switf'li.; From. the.

it will be' seen thatr the piston 57 controls the f .excitation or' the winding 4- controls the excitation o't winding 65, which Y in zturn vcontrols the excitation of winding t, and contact 88 33 through the actionof'contactor 6st and contact 63.v Y Y f. The gei'ieral sequence ot operations/1n ymaking` an" automatic application oitl the brakes is as follows: The winding 52, which isv normally energized, Hence valve 59 opens and f remainsy open,

and main reservoir'air sliiitts pistoni-6V Soi that the rotary valve 171s turned toservice application positioinfwhere remains; So

longas the valve Oreii'iains open thevalve cannotv be restoredto release or rf'iinning position, the port 56 being vei'yniinute and in-v sufficient to coi'interact Athe feed through thc valve 50. This immediately lowers the pressure above the equalizing dischare piston 26,50 that the equalizing discharge valve 2aopens and flow 'from the port 25"'coinmences.

. Almost instantly. therefore, the piston 58 is forcedv down, bridging contacts 60 Vand 6l p and exciting the rindiiig` 77'. Consequently,l before Vany substantialv flow from the ,shellk has occurred, the valve 75 closesV and ison lates the two chambers within theV` drinn from each other.'r The pressure in the left hand; chamberfdrops gradually through the action of 'the preliminary exhaust port 21',

; while thefpressure to the'right of the partipreliminary. exhaust port 21 ceases.

tion 71 remains' constant. A. point is there- Jtore reached when the loading sprii'ig Sil is overpowered and the contactor 8S. bridges the contacts and 91. I Ordinarily the parts wouldibe adjusted so that thiso'ccursatter a-Freduction of about eightpounds has been made. l

The bridging ofthe contacts 90 and 91 Y .excites the winding 6,5 and the contactor 64 moves upward, closing the circuitwith the contact 63 in the short period otfroin one to twoseconds. During this interval the pressure in the vequalizing reservoir may 4have dropped a pound or so, but bythe time a ten pound reduction has been made winding 33 is energized andr the efhaust through the In' a short time brake pipe pressure and'equalizing 'reservoir pressure will be balanced, piston 26 will move downward, and therequalizing discharge valve Y24 will close, whereupon fthejpiston 58 will move upward, deenergizying winding 77. lThis causes the valve .75 to shell 70 is complete,`but the delayed action `is I deenergized.

The approaching `equalization in" .occasionedhy the dash plot holds the circuit through contacter 64 and winding33 vclosed c for several Y mit complete equalization-to occur.

When the circuit is interrupted at 64; and winding 33 is as a consequence deenergized,`

thefralvel again opens, once. lmore Event-ing the shell 70,- and as a Vresult starting adis-l charge `through the eouializing. ,discharge` VJf'alv'e241'. This discharge acting' on the pis- `'ton-56 results in a repetition of the functions already described. `so that the pressure'ion theequalizing discharge piston 26 .is'refduced by'siiccessive steps ofl say ten pounds each.

The engineer cannot prevent tlieirst reduciion, but he can prevent reduction subsequent to the viii'st by closing the pushfswitch 6.2 which has'the effect Vof maintaining the winding TT constantly `en`ergized,"th`us preventing equalization between the-twor'cham- .bers ol' drum 70 from occurring.

lhe above described mechanism can. be put automatically,into action by a number ot train .control'vdevicesL The wires 97and '99 maybepermanently connected to theopposite poles ot the battery or otherrv source seconds, a time sutiicient to per ol2 current, and there shouldbe some autoi -niatic means to interrupt ail-energizingcir- `cuit i'or the solenoid `52 and simultaneously to su p plyY electric energyto the wire 95. It is volwicusly necessary that wire/95 'be inert-except during automatic applications, .asotherwise the automatic split reduction cycle would be imposed tions of the brake.

Any Asystem which will-meet the require- V' ments above outlined might be used, and it is obviously possible to make use'oftrack trips, track contacts, radiant.energy` transmitters, inductive mechanisms, orany other Vknown meansvfor transferring energy from the points on the track to'thepassingitrain.

Special operativerfunctions and Vadvantages are, however, secured by thejcombina-- tion ot the'inechanism already described during `manual 'applica-f 'ion with an inductive impulse mechanism 'otra4 typewliich heretofore, iii-its general aspects at least, has been known. l i

Such ai mechanism is shownin Figure 2 andwillnow be described in detailf single` battery 101 is used as the sourceiof all the elect-ric energy used toactuate the traincarried part of themechanism. The wire 99 is connected toonepole and' the-wire 97 is connected to "the other pole .of the battery'.

The connection otthe'wire 97 is notr direct, but is througha reversing` switch l02ihereinafter referred,V to morein detail. rEhe connection need not bethrough such areversing switch, .but it is convenient to make it sobecause in an intermediate position ofthe switch all the operative circuits are.` interrupted and it is desirable to interrupt the batteryA circuit at' the same time. n .Y vThe ywire 97 isalso connected.tothecoutactor arm 108 of a speed responsive syvitch.

tration is diagrammatic. only. v'lhesWitcla Ais f so contrived that 'when the train lis at rest contactor arm 193 is toit-lie lrightandfhorizontal. It is then in contact-with three arcuate contacts ot' `drterent angular extent,

namely, the danger'limitA contact? 104. a

longer caution `limit cont-act '105, vand :a 'ill longer speed lmnt Contact 106.v increasesdi'ts speed memng v1n' either Vdirecl tion, the arm 103 swings in a counter-cloclcclears the Contact 1011. it the limiting-speed at which it isA desired 4to permit a train 'to )enter a .block against a caution signal .setv

against it, it *overruns Vthe endV of the con'- tact 105. At the limiting speedl Whichit 1s desired .to permit a train to be operated under ,any circumstances it overruns thel end .of the contact 10G.

Contact 10i-is connected by a. wire 107 With a reset button 1'09 which whenA closed will ,prevent the'danger relays from op'erat-` ing, or. if theyhave ope-rated, will restore `the/same. Gbyiously the switch 109 isef-V :ective only below the danger rvlimit, 'torl`above .this limit the Aarm 103 clears the 'conl.tact-104;. i i V 1 Contact 105 is connected by a Wire 108 y with a reset 110v similar in function but `cleaV switch by signed to reset the l Winding' is 'shown at alternatively with .an upper caution relays in opera-y tive position provided the train speed below the caution limit. n H r-llhe Contact 106 is a part-of the main ac# tuating 'circuit-s.v Thus, `When-the arm 103 .overruns the Contact 10,0, brake application y inevitably follows.,V y v Remembering that varm 103 is'conneicted to wire 97., which leads to one poleof the! battery, thecircuitran be traced through convtact 10,6` Wire 111, to armature 112, of what is vcalled theV secondary danger relay, vWhose l113.V Thearmaturev 112 l moving into Contact contacftflle and a lower conta-ct 115. The lower Vcontact 115" is connected throughra danger lsignal lamp 11G 'with wire 95, alreadydescribed. r The upper lContact 1111s connected'by a Wire' :11T with an armature 118 of `what is ,known acts as 'a switch by y-as aseconda-ry caution relay Whose Winding is shown at 119.v rlfhe armature .-11Sactsas per Contact and a lower contact 121. The lower Contact. 121 isconnected through a caution signal lamp 122 Withiw'ire 95. The upper contact 1210 is connected by a Wire with the :Winding` 52 from which wind-V ing there isa return wire 124 connected to4 one terminalof each of the Windingsll and 119, and :also to the second-pole'of the If the train Y' 'wire reversing switclii`f102 abofye vmenticned;4

one terminal oit; Windingl129 Vis Contact alternately with-an upfv4 g y l Y vconnect-ions and 143,"anl `a p turn rconnection 141 'for #two impulse gen-f which til-1e @Wire 97 leads.

Under normal .operati-ng conditions/the armatures-112ffandf118 .are vinrtheir upper `ine,diatefly energizes l.the `Wire x95, lighting, the appropriate sig-nail' lamp to indicate'that :the

engi-neer has passed a danger signal lor lcaution signal A*set 'against -as'qthe case fmay VEach of fthe windings 113and 1-'19fis con'- "trolled aislto excitationby @a 'conres'ponding v pril-nary relay.- 'The primary' :dangenrelay include-s -a Winding :12.5, combined ,vs-witch.

i Si

and armature i126', and fa contact` 127,1 With .y

connected by 'af-wire 128'wi'tli the secondterminal ofthe winding 113, the other ter! -minalot Winding 113 beingconnectedfto the wire 11211 as explained'. v Y ,Y

ll-lie primary" caution relay includes a` Winding 129,?a combined fswlitch'zand-"armajture 130.,"snd-'a contact 131 `with Wrliichthis 1 cts. VThe -lcontact 1311s 'connectedby'ja 1re 132 -iyith'the k.second terminal Volfjfthe Winding1519, ift bei-.ng remembered that ,the

Yfirst terminal of ltfhe Winding 119 is connect- Ved 'with the Wirev 1211., The armatures 1126 armature 126 Vor 130 ndrops, .theavmdingl'l l *or thewinc'ling 119,;as the casemay be, 'will' 'befdeen'ergized. f

As 4Will ihe explained, nei-ther ythe armatiire 120 nor the,arma-ture '130 lis capable "of re- 'settingitseli sothat-Lthe drop-ping of :either armature entails'a sustained deenergization "of the :corresponding v'Winding 113 Ior .119. `"lhis'result iis-'secured by ipafssingthe exciting "current =or the'iwindilngs' 1125 Y and 129 *through their respective armatures 126 'and 130. Thnsfone terminal of Winding is connected to VWire 128 le-y Wire-134,2rnd the oth'erfe'nd of 'the `Winding' is connected by with 'a `'middleV contact 13,6 kof the Similarly, connectedl ya-Wire 13.7 with Wire 132-. The other isli'onnec'ted by a Wlire V11238 Wi other 'middle contact 1139 off the* reversing Wire 141.* 4The .reversi-ng s-'Wltc'h 102 controls As clearlyys'ho, v"-n .in Fi-gure- 2; the reof contacts :which fina-y be 4connected alterlcommonl ere# lio are cross connections betweenthe upper row and lower row, so disposed that the effect of connecting the middle row `with the upper row or the lower, row is alternately to transposejor interchange the coils 145 and 146 Vwith referencefto the windings 125 and 129, l'l`livis'is'necessary, because the track equip-V ment at one side of the track is for danger indications, and at the other side is for caution indications. n I headed in either direction on the track, it is Since the train maybe necessary at times to transposethe coils 145 and 146 in order to establish the pi'op'eijie-Y lation between the` caution and 'danger'ap paratus oii'the train, and the caution and danger apparatus on the track. SuchV reversing switches are common in the Vart and no detailed explanation seems necessary. I

middle row and'lower row ot' contacts arev It will be assumed from-now on that the normal connection is 1n eftect, in which the connected with each other, lso that the coil 145 is associated witlitlie relay` 125and the coil 146 is associated with the relay 12S).

In such case the` wire 135 connects directly with the wire 142, wire 138 connects direct lyfwith the wire 143, and the common return from theV winding 1,45 rand 146 is established through the wires 144k and 141 to the return leadv 99.l

uThe coils 145 and146 are wound o'npcores having pole `pieces'147Y and 148 respectively,

which are Alocated between the rails and slightly .above the topsrthei'eot. pieces and windings are carried by adjustable brackets 149, and 150 of magnetic material, and these brackets are carried by yokes 151 which arch, over the wheels 155 land 156 and are supported on'tlie journal boXes152. The yoke 151 also Vcarries a collar-153 which surrounds the axle 154 freely but so closely as to provide arelatively small air gap between thevcollar 153 and the axle 154,V I

Remembering that they-axle and the wheels are of magneticmaterial and that the wheels f arey fixed on tlieaxle',jtwo distinct magnetic above defined as to generate in one or anl Yother coil 145 or 146, upon passage kof the train, an impulse of such character aswill deenergize the relay winding 125 or 129, as

pathslare aifordedthrough the` cores, brackets, collar, airle'and wheels.l

The track equipment consists ozt v anyl Vmeans fors'o passing magnet-iclines o1 torce through either of the twoniagnetic paths the case may be, and cause the corresponding armature 126 or 130 to drop. A

It has been explained that the buttons109 and'110 may .be closed 'to prevent the armature from dropping, .providedtheV arm 103 is -in contact with the contacts V104l or 105, as the case may be.

cause 'theswitcliesp109,` 110`establish acon7k nection to theV wires 128 and 132 respective-v tends inward therefrom.

Therv pole" This resultA is l secured Ybe#`V ly, and thus maintain the the windings 125', 129.V

energization i of Y The track equipment consists of two perf manent magnets, one for danger indications* and the other for caution indications, each having a neutralizing winding which renders the permanent magnet ineii'ective when the corresponding rnentri-lizing winding is 'The track i-ailsare shown `at 157 and 158, Vand a tie is indicated at 159. The,bar 160is fixed to the base of rail 157- and eX-l This vbar is of magneticmaterial, and-forms an extensions:`

voli a peiinaiient magnet 161 which liasat its opposite endacore extension terminating in a pole piece 162, opposed to the pole piece 14'( 'of the trani carriedcoil 145. The wind- -ing 168 on this core maybe energized by a battery 164 under-the control of a switchV This switch is under the control of the danger signal, is closed during clear indications, andropen during. danger indications.'

A substantially identical caution unit is viiitedto the base of' the iail'158 and includes a bar 166perinanent magnet 167, pole piece 166, (opposed to polepiece 148) winding 169, battery 170,' and 'A switch 171.7`

The switch 171 is connected so as to be open during caution indications and closed when the caution signal gives a clear indication. Ii: both the switches 165 yand 171 are closed when a trani passes, permanent magnets 161 and 167 are inert and no impulse is transpulse ,willv beV generated which neutralizesi fthe eiicitation ot' winding 125'and'causes armature 126 to drop. This iinmediatelyde- `energizes winding 1:13' 'of the Asecondary relay, vcausing armature 112 to drop. This deenergizes winding 52, lights signal lampi 7 116 vand"energizes'the wirev 95. y Y

'ihe iinniediateeti'ect is to canse lthe piston ltofshit't'the engineers brake valvens already described, aftei' which the piston` 58 is (ilepiessed, winding 7T energized, the'valve 75 closed, and the reduction liiniting'niecha. nism' rendei'ed eil'ectiive. Wlhenthe desired reduction has been made, the diaphragm A78 operates to establish connection through contact 86,the timeY switch is closed,` therednctioii terminating valve closes,fand the first step'o't the split reduction is completed.

The engineer can pieventasecond reduction by closing ythe switch 62, but i'fhe does not the device will automatically go through Y i a 'second and other succeeding reductions 1 the second electromagnetically actuated valve. -fA j f Y Y c The combination ot an engineersbrake vvalve ot ,the equalizing',discharge type including an equalizing discharge. Valve, piston and preliminaryY exhaust port; a control Adevice operable to shift saidbiake valvefto an application position in which said preliminary exhaust port is open; ali-independent valve controlling said preliminary exhaust port;v an equalizring'reservoir; and a device rendered active by tlieaction of said control'device; and including means responsveto agiven reduction of pressure in said reservoir 'for closing said independent valve, and adevice responsive to the resulting cesI- `.sation of flow through the equalizing discharge valve and serving to reopen said in dependent valve.

8. The combination ot' an engineerls brake rvalve of the/equalizing discharge type inv*cluding an equalizing discharge valve, pis-A ton andprelin'iinary exhaust port; a motor operable to sliittsaid brake valve to an application position in which said preliininL ry exhaust port is open; an elcctromagnet windingnorinally excited and wheny excited Vholding' said motor inactive; a -nori'nally open independent valve controlling said preliininary ,exhaust port; an electromagnet Y winding for operating 'said independent Yvvalve; an equalizing reservoir; a control de vice operable to deenergize the 1first named winding and simultaneously establish a supply ot' current for the second named.wind-l ing; a pressure actuated switch subjectv to the pressure in the equalizing reservoir and jarranged to close upon a given reduction of pressure to connect said current supply in exciting relation with the second winding; and

.a second switch 'subject to the pressure ot air discharging through the equalizing discharge valve, normally open unless held closed thereby, said switch when open interrupting the exciting circuit for the second namedwinding, and setting the lirst named switch in circuit opening position.

v. 9; The combination ot an englneers brake kvalveo'l' the equalizing .discharge typerincludingan equalizing discharge valvc pis- .t'oirand preliminary exhaust port; a. motor operable to sliift'tsaid brake valve to an ap- ;'plication position in which .said preliminary exhaust port'is open; af normallyopen'elec- `tro-magnetically actuated reduction tei-ini? nating `valve controlling said preliminary :exhaust port; a pressureactuated switch arranged' tobe closed by air discharged by said equalizing discharge valve; an veoliializing reservoir comprising two chambers normally Y" in communication Witheacli other; an electro-magnetically actuated isolating valve controlling the communication between said chambers; a reduction limiting switcl'i;V adiaphragm subJect to the opposing pressures in rsaid'two chambers and connected to actu- Vate said reduction limiting switch; a de` layedaction relay switch;- electrical connec` VJtions whereby the pressure actuated switch controls the isolating valve, the reduction limiting switch controls'th-e relay switch and 'the Arelay switch controls reduction terminating valve; and a control device operable to actuate said motor andl simultaneously supply electric energy to said connections.

l0. The combination of an engineersv ing the recurrence of brake applying tlow alter automatic interruption thereof. Y

ll. rl"he combination of an engineers brake valveot the equaliziiigv discharge type including an equalizing discharge valve;` a control device operable tov shift rsaid brake valve to van application position; meansren.`

dered active by. said control device in so shitting said brake valveand serving when active to close the equalizing discharge valveperiodically, while the brake valve remains in` application position; andman'ually oper# able means :for preventing the equalizing 'discharge valve from-reopening after closing. Y lf2. The Vcombination `olf`Y an engineei"s brake-valve oi' the equalizing discharge type,

including an equalizing discharge valve, pis-V ton andr preliminary exhaust port; a control device operable to shift said brake valve to'an application positioninnf'liich said pie-rliminary exhaust portis open; an independ`v 'ent valve controlling saidvpi'el'i'niinary exhaust port; means rendered active byisai'd control device in so shifting saidfbrake vvaliv'eyand serving wlienactive to close said,V

independent valve periodicallyj while the brake valve remains in applicationv position; andvn'ianually operable means 'for rpreventing the reopening of said independent valve after any periodic closure thereof. Y n

In testimony whereof wefhave signed ournainesto this sliecilication.

@Hannes A A. CAMPBELL.

ERWiN-o. vROMaN. 

